Ritual of Fitr Prayer

In the late Ramadhan 202 A.H. / March 817 A.D., Mamun sent a message to Imam Reza (A.S.) requesting His Holiness to conduct the religious service of the celebration of "Fitr Prayers" (Festival at the end of the month of fasting) in Marw.
The Holy Imam (A.S.) did not first accept that task, but due to Mamun's insistence His Holiness consented to perform the related ritual just on the basis of the method the Holy Prophet of Islam (S.A.W.) used to practice. Mamun accepted Imam Reza's (A.S.) suggestion concerning this issue.
Early in the morning of the celebration day of "Fitr" the horse of the caliph ornamented with glossy galloon was waiting at the gate of the Holy Imam's dwelling place. The high-ranking officials of the state such as military commanders, senior judges, distinguished savants and celebrated authorities of Marw were all in costly costumes waiting to escort His Holiness. Large numbers of people were waiting here and there, even on the roofs of their houses to visit and welcome the Holy Imam (A.S.).
Unexpectedly His Holiness appeared in plain clothing and bare-footed before that congregation, attended by his own men who were in simple garments and bare-footed.
The Holy Imam (A.S.) bare-footed marched forward and glorified God loudly; saying "Allah Akbar" (God is the Greatest of all).
When the officials saw Imam Reza (A.S.) in simple clothing and bare-footed, hurriedly jumped down from the saddles of their horses and tried to take off their boots.
The Holy Imam (A.S.) continued glorifying God by repeating the phrase "Allah Akbar" (God is the Greatest of all).
One would probably say an earthquake had unexpectedly occurred in Marw; from every direction the call "Allah Akbar" could be heard, and during his graceful marching the Holy Imam (A.S.) loudly glorified God, and the congregation present there followed His Holiness and shouted "Allah Akbar".
The magnificence and splendour of that demonstration was rapidly related to Mamun, and the rally was reported as an alarm for the caliph. He quickly dispatched one of his men to request the Holy Imam (A.S.) to cease the continuation of that ritual under the pretext of some excuses Mamun had verbally invented. Despite being deeply annoyed Imam Reza (A.S.) , left the place and the people, who had now turned into a fiery mass.